Project Summary In mosquitoes and model invertebrates, the midgut functions as a center for insulin/insulin growth factor signaling (IIS). The effects of IIS from nematodes to mammals are largely mediated through mitochondrial dynamics and activity, defined as mitochondrial biogenesis, bioenergetics, and clearance of damaged mitochondria through mitophagy. In both invertebrates and mammals, IIS-dependent mitochondrial dynamics and mitochondrial metabolism regulate a wide range of important physiologies, including epithelial barrier integrity, stem cell maintenance and differentiation, reproduction, longevity and immunity, indicating that this regulation is fundamental in living organisms. In Drosophila melanogaster and Caenorhabditis elegans, tissue- specific changes in mitochondrial function contribute to an interorgan signaling network that underlies these essential physiological processes. In particular, the fruit fly gut and nematode intestine, tissues exquisitely sensitive to stress, are intimately involved in organ-to-organ communication via local mitochondrial changes that alter systemic mitochondrial function. Given this biological conservation, our overarching goal is to broadly expand our understanding of mitochondria as master regulators of physiology in hematophagous insects of medical importance. Based on our own data and significant data from the literature and model organisms, we hypothesize that changes in the midgut mitochondria of the mosquitoes A. stephensi and A. aegypti control midgut health locally and this information is communicated systemically to control mitochondrial function and health of other tissues. Further, we hypothesize that life history trade-offs in resistance to infection, longevity and reproduction in A. stephensi and A. aegypti are fundamentally controlled locally by the midgut and coordinated systemically by mitochondrial interorgan signaling. We will test these hypotheses in three Specific Aims. In Aim 1, we will define midgut mitochondrial control of midgut health through the generation of transgenic A. stephensi and A. aegypti that overexpress gene products regulating mitochondrial biogenesis, electron transport chain protein levels and activity, mitochondrial fusion and function, and mitochondrial quality control through mitophagy. In Aim 2, we will use the transgenic mosquitoes developed in Aim 1 to define midgut mitochondrial control of systemic mitochondrial activity and fat body, flight muscle, and brain tissue health. And in Aim 3, we will use our transgenic mosquitoes to identify the networks of mitochondrial signaling that coordinately control longevity, reproduction, and resistance to pathogen infection. These phenotypes are manifested as life history trade-offs that we hypothesize are fundamentally controlled by mitochondria. By the end of these studies, we will understand how midgut mitochondrial function affects local midgut health and controls interorgan signaling to regulate and coordinate life history traits critical to vectorial capacity.